Blender no longer opens my blend file, it loads the Export FBX screen and is stuck there
Open the file without the Load UI option ticked

Go to File > Open and browse to open your desired file, but before you open uncheck the Load UI option on the bottom left of the File Browser window.

If not, open a new Blender instance and append your scenes from the previous file.

Otherwise post your file here so we can look at it.